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Studies of the Phoront of Hyalophysa chattoni (Ciliophora, Apostomatida) Encysted on Grass Shrimp 1
Author(s) -
LANDERS STEPHEN C.
Publication year - 1986
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1986.tb05660.x
Subject(s) - metamorphosis , shrimp , ecdysis , biology , larva , muda , moulting , zoology , host (biology) , decapoda , ecology , crustacean
. The apostomatous ciliate Hyalophysa chattoni , an ectosymbiont of the grass shrimp Palaemonetes pugio, encysts and dedifferentiates within 48 h from the migratory tomite to a phoretic stage devoid of complex ciliary fields. The presettlement crawling and pivoting of the tomite may play a role in its initial attachment to the shrimp. Metamorphosis of exuviotrophic apostomes has been previously observed to take place immediately prior to host ecdysis. The study has found that Hyalophysa's metamorphosis to the feeding stage on grass shrimp is initiated by a cue from the premolt host and begins during earlier stages of the molt cycle (D 0 and D 1 ). Due to the long premolt stage of the host's diecdysic molt cycle, metamorphosis is initiated well before ecdysis (over six days). Hyalophysa was able to encyst and metamorphose within 41/4 h when exposed to shrimp in a late premolt stage, indicating that the control of apostome metamorphosis is solely host‐dependent.